I was asked on Tumblr what I would say is the most sacred place for Hellenic Polytheists. I know they're looking for a temple or sacred site as an answer (and try the Acropolis, or any of the old temple sites for that... Delphi even...) but to me, the most sacred place for Hellenic Polytheists is their home, their oikos. Even in ancient times, the majority of daily worship took place there, and it was where the most personal of connections was made with the Gods.

Back in ancient Hellas, most religious activities surrounding the household revolved around the central hearth, which was the physical manifestation of Hestia. The male head of household, the kurios, presented slaves, children and his new wife to the heart fire so they became part of the oikos and fell under the protection of Hestia and the other household Gods.

The courtyard of the home often held a bômos, a free standing, raised, altar where the majority of household worship took place. Some houses also had a wall niche, an indoor worship area, either in a room especially designated for worship, or in the main family room. These altars were used to worship the Ephestioi (Εφεστιοι), the most personal of the household Theoi. These almost always included: Hestia, Zeus Ephestios (Overseer of the Hearth), Zeus Kthesios, and Agathós Daímōn. Worship of these deities was highly personal, and many other Theoi could be added to this worship list.

Hestia was represented by the hearth fire that was always kept burning. If it went out, the male head of household would go to the prytaneion (Πρυτανεῖον), the structure where state officials met and where the city kept a fire for Hestia burning day and night, for a new flame. All fires in the house were lit from this one fire, so Hestia would watch over everything and everyone inside the house. Zeus Ephestios was and is a more active defender of the home. He shields the actual structure of the house. Where Hestia watches over the occupants, Zeus Ephestios guards the very walls, the roof, the floor, and any possessions inside the structure. He was worshipped at the main altar.

Zeus Kthesios guards the pantry, and was honored there as well, where he had his own shrine, often adorned with a kathiskos. Agathós Daímōn and the ancestors were also worshipped at the main altar, although they may have had small shrines to themselves, especially in the case of wall niches.

In the courtyard of the house, the Herkeioi (Ἑρκειοι) were honored: those of the herkos or front court. Most notably, this was Zeus Herkeios (Ἑρκειος), protector of the enclosure of the house. And just outside the house, and especially near the gate to the street, small shrines and altars were placed in honor of the less personal protectors: Apollon (sometimes in his epithet of 'Aguieus' (Ἀγυιεύς), protector of the streets, public places, and the entrances to homes), Hermes Propylaios, Hekate, and especially in Sparta, the Dioskouroi. Hēraklēs sometimes took the place of Apollon.

Zeus Herkeios' altar stood in the courtyard and He, from the inside of the house, protected against anyone wanting to harm the house or the family living in it. These altars were most often pillars, on or around which the offerings could be placed. Hermes, Apollon, and Hekate were represented by a pointy four-sided post. The top was reserved for Apollon, the bottom often held a niche where Deipnon offerings could be placed to Hekate, and Hermes' face (and sometimes his genitalia) was  carved into the post. Hermes sometimes got his own post, called a 'herm', which was a rectangular post, with His face carved on top, and his genitalia carved out on the front.
 
Temples were of great importance to the many festivals of ancient Hellas, but nowhere was the worship of the Theoi so varied and extensive as in the home. Especially for modern practitioners who often lack temples and community, their own homes are the focal point of worship--as it should be, because at its core, Hellenismos is a household religion--a family religion--and I think that's beautiful.